    import java.security.Key;  
    import java.security.SecureRandom;  
      
    import javax.crypto.Cipher;  
    import javax.crypto.KeyGenerator;  
    import javax.crypto.SecretKey;  
    import javax.crypto.SecretKeyFactory;  
    import javax.crypto.spec.DESKeySpec;  
      
      
    /** 
     * DES安全编码组件 
     *  
     * <pre> 
     * 支持 DES、DESede(TripleDES,就是3DES)、AES、Blowfish、RC2、RC4(ARCFOUR) 
     * DES                  key size must be equal to 56 
     * DESede(TripleDES)    key size must be equal to 112 or 168 
     * AES                  key size must be equal to 128, 192 or 256,but 192 and 256 bits may not be available 
     * Blowfish             key size must be multiple of 8, and can only range from 32 to 448 (inclusive) 
     * RC2                  key size must be between 40 and 1024 bits 
     * RC4(ARCFOUR)         key size must be between 40 and 1024 bits 
     * 具体内容 需要关注 JDK Document http://.../docs/technotes/guides/security/SunProviders.html 
     * </pre> 
     *  
     * @author 梁栋 
     * @version 1.0 
     * @since 1.0 
     */  
    public abstract class DESCoder extends Coder {  
        /** 
         * ALGORITHM 算法 <br> 
         * 可替换为以下任意一种算法，同时key值的size相应改变。 
         *  
         * <pre> 
         * DES                  key size must be equal to 56 
         * DESede(TripleDES)    key size must be equal to 112 or 168 
         * AES                  key size must be equal to 128, 192 or 256,but 192 and 256 bits may not be available 
         * Blowfish             key size must be multiple of 8, and can only range from 32 to 448 (inclusive) 
         * RC2                  key size must be between 40 and 1024 bits 
         * RC4(ARCFOUR)         key size must be between 40 and 1024 bits 
         * </pre> 
         *  
         * 在Key toKey(byte[] key)方法中使用下述代码 
         * <code>SecretKey secretKey = new SecretKeySpec(key, ALGORITHM);</code> 替换 
         * <code> 
         * DESKeySpec dks = new DESKeySpec(key); 
         * SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(ALGORITHM); 
         * SecretKey secretKey = keyFactory.generateSecret(dks); 
         * </code> 
         */  
        public static final String ALGORITHM = "DES";  
      
        /** 
         * 转换密钥<br> 
         *  
         * @param key 
         * @return 
         * @throws Exception 
         */  
        private static Key toKey(byte[] key) throws Exception {  
            DESKeySpec dks = new DESKeySpec(key);  
            SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(ALGORITHM);  
            SecretKey secretKey = keyFactory.generateSecret(dks);  
      
            // 当使用其他对称加密算法时，如AES、Blowfish等算法时，用下述代码替换上述三行代码  
            // SecretKey secretKey = new SecretKeySpec(key, ALGORITHM);  
      
            return secretKey;  
        }  
      
        /** 
         * 解密 
         *  
         * @param data 
         * @param key 
         * @return 
         * @throws Exception 
         */  
        public static byte[] decrypt(byte[] data, String key) throws Exception {  
            Key k = toKey(decryptBASE64(key));  
      
            Cipher cipher = Cipher.getInstance(ALGORITHM);  
            cipher.init(Cipher.DECRYPT_MODE, k);  
      
            return cipher.doFinal(data);  
        }  
      
        /** 
         * 加密 
         *  
         * @param data 
         * @param key 
         * @return 
         * @throws Exception 
         */  
        public static byte[] encrypt(byte[] data, String key) throws Exception {  
            Key k = toKey(decryptBASE64(key));  
            Cipher cipher = Cipher.getInstance(ALGORITHM);  
            cipher.init(Cipher.ENCRYPT_MODE, k);  
      
            return cipher.doFinal(data);  
        }  
      
        /** 
         * 生成密钥 
         *  
         * @return 
         * @throws Exception 
         */  
        public static String initKey() throws Exception {  
            return initKey(null);  
        }  
      
        /** 
         * 生成密钥 
         *  
         * @param seed 
         * @return 
         * @throws Exception 
         */  
        public static String initKey(String seed) throws Exception {  
            SecureRandom secureRandom = null;  
      
            if (seed != null) {  
                secureRandom = new SecureRandom(decryptBASE64(seed));  
            } else {  
                secureRandom = new SecureRandom();  
            }  
      
            KeyGenerator kg = KeyGenerator.getInstance(ALGORITHM);  
            kg.init(secureRandom);  
      
            SecretKey secretKey = kg.generateKey();  
      
            return encryptBASE64(secretKey.getEncoded());  
        }  
    }  